The present invention relates to a modular shelf system and, more particularly, to a joint structure employed in the system to hold abutting shelves against edgewise separation. In one such system, the joint structure includes abutting, planar shelves sandwiched between vertical supports extending both upwardly and downwardly from the shelves. Connected between the upper and lower supports is a fastening member for drawing the two supports toward each other to clamp against the shelves. In assembling the shelf system, open-sided holes in the edges of the abutting shelves are aligned, facing each other to receive the fastening member. A groove formed in each shelf concentric with the hole receives an annular boss projecting downwardly from the lower end of the upper support to hold the shelves against edgewise separation once the supports are drawn tightly against the shelves by the fastening member.
A joint structure of the foregoing type is disclosed in Kellogg U.S. Pat. No. 3,831,533.